Delete dead code
Delete dead code

Summary:
The delete_dir function isn't referenced anywhere, and it's not even defined. Delete its declaration.

This diff should not change behaviour.

Reviewed By: wez

Differential Revision: D8728076

fbshipit-source-id: 73453a079e80f94376637e6687bedc3f405f8502

wez/watchman,nodakai/watchman,nodakai/watchman,facebook/watchman,wez/watchman,facebook/watchman,nodakai/watchman,wez/watchman,nodakai/watchman,facebook/watchman,facebook/watchman,wez/watchman,facebook/watchman,nodakai/watchman,facebook/watchman,wez/watchman,facebook/watchman,wez/watchman,nodakai/watchman,facebook/watchman,nodakai/watchman,nodakai/watchman,wez/watchman,facebook/watchman,wez/watchman,nodakai/watchman,wez/watchman